1. Field of the Invention
The present invention relates to the fabrication of integrated circuit devices on semiconductor substrates and, more particularly relates to methods of forming a contact structure, contact structures and apparatuses for forming the contact structures.
2. Description of the Related Art
The Complementary Metal Oxide Semiconductor (CMOS) technology has been recognized as the leading technology for use in digital electronics in general and for use in many computer products in particular. The miniaturization of CMOS technology according to a scaling rule is used in a semiconductor device to achieve large-scale integration and high-speed operation. For the miniaturization of CMOS devices, metal contacts have been widely applied in this industry.
FIG. 1 is a schematic cross sectional drawing showing a contact structure. The contact structure comprises a substrate 100, a dielectric layer 110, a metal contact 120 and a metal oxide 120a. The dielectric layer 110 is on the substrate 100. The metal contact 120 is formed in the dielectric layer 110. The metal oxide 120a is on the metal contact 120.
The method for forming the contact structure comprises providing a contact hole (not shown) in the dielectric layer 110. A metal layer (not shown) is filled in the contact hole and over the substrate 100. A chemical-mechanical polishing (CMP) process is then applied to the remove the metal layer which is above the surface of the dielectric layer 110 so as to form the metal contact 120. After the CMP process is performed, chemicals of the slurry used therein react with the metal contact 120. As a result, the metal oxide 120a is formed on the metal contact 120. Due to the high resistance of the metal oxide 120a, the resistance of the contact structure increases and may cause the failure of the circuit. Cleaning methods with chemical such as water or ammonia have been applied to the post-CMP contact structure in order to remove the metal oxide 120a. 
U.S. Patent Application Publication No. 2002/0052115 A1 discloses a method of eliminating agglomerate particles in a polishing slurry. The method comprises conveying the waste slurry to the drain, wherein the waste slurry may form an agglomerate having an agglomerate particle size. The method further comprises subjecting the waste slurry to energy emanating from an energy source. The energy source thereby transfers energy to the waste slurry to substantially reduce the agglomerate particle size. By substantially reduced, it is meant that the agglomerate is size is reduced such that the waste slurry is free to flow through the drain.
U.S. Pat. No. 5,906,949 discloses a CMP process. The process is performed using a slurry containing abrasive particles mainly made of sialon or boehmite. This process is advantageous in improvement of a polishing rate without degradation in planarity of the processed surface and in level of metal impurities.
None of these applications address the problem described above.